Narrative:

In level cruise at FL410 the first indication of a problem was monitor warning; left; failure. Immediately after was followed by numerous cas messages to include; mau 1 and 2 fail; primary pitch trim failure; loss of PIC primary flight instruments; intermittent loss of sic flight instruments; FMS 2 blank; FMS 1 not blank; however couldn't input any data; pressurization spikes; and cabin altitude warning at appx FL180. We initially asked for a lower altitude with center; then after transferring flight controls to the right; we declared an emergency due to the pressurization spikes and multiple system failures. Descending thru FL180 we received a cabin altitude warning and both oxygen masked were donned until we descended below 10.000'. At approximately 4000' as we turned on to final; both mau [modular avionics unit] malfunctions cleared and normal indications appeared on all flight instruments. The autopilot was not engaged; and we made an uneventful landing. During our descent; we attempted to complete the abnormal checklists; however; the multiple cas message made that difficult to decipher what actually was the problem. From my experience I judged it to be a mau failure; in this case; multiple mau failure. However at about the time that I went for the checklist to address the failures; we received the red master warning cabin altitude. Both pilots donned the masks and continued our descent to our cleared altitude of 9000' where they were removed. We attempted to get the cabin to depressurize before landing. Descending thru approximately 4000'; the failures cleared; the approach was loaded into the FMS; and a normal landing was made. Emergency services followed us to the ramp; and nothing abnormal was noted on the exterior of the airplane. All throughout the event the passengers were comfortable and we made them aware of the situation as we had time.after speaking with maintenance control; I was informed that this tail number had previously had a mau failure. The controller said that after 10 hours of test flights they were unable to reproduce the failure. In order to help the crews know more about the different tail numbers that we fly; there needs to be a process [to check maintenance history]. We should be able to enter a tail number which we are assigned and review not only the current documents onboard and pass-down information but also recurring maintenance actions and abnormal maintenance irregularities for the previous 60-90 days. When the maintenance log sheets are removed from the aircraft; we are unable to see the full picture of the airplane and troubleshoot any minor problems.

Related reports:

Google
 

Original NASA ASRS Text

Title: CE680 Flight Crew at FL410 experiences multiple failures possibly associated with MAU 1 and 2 failure. Pressurization is lost and flight diverts to a suitable airport. All failures cleared before landing and post flight checks revealed a history of MAU failures.

Narrative: In level cruise at FL410 the first indication of a problem was monitor warning; left; failure. Immediately after was followed by numerous CAS messages to include; MAU 1 and 2 fail; primary pitch trim failure; loss of PIC primary flight instruments; intermittent loss of SIC flight instruments; FMS 2 blank; FMS 1 not blank; however couldn't input any data; pressurization spikes; and CABIN ALTITUDE warning at appx FL180. We initially asked for a lower altitude with Center; then after transferring flight controls to the right; we declared an emergency due to the pressurization spikes and multiple system failures. Descending thru FL180 we received a CABIN ALTITUDE warning and both oxygen masked were donned until we descended below 10.000'. At approximately 4000' as we turned on to final; both MAU [Modular Avionics Unit] malfunctions cleared and normal indications appeared on all flight instruments. The autopilot was not engaged; and we made an uneventful landing. During our descent; we attempted to complete the abnormal checklists; however; the multiple CAS message made that difficult to decipher what actually was the problem. From my experience I judged it to be a MAU failure; in this case; multiple MAU failure. However at about the time that I went for the checklist to address the failures; we received the red master warning CABIN ALTITUDE. Both pilots donned the masks and continued our descent to our cleared altitude of 9000' where they were removed. we attempted to get the cabin to depressurize before landing. Descending thru approximately 4000'; the failures cleared; the approach was loaded into the FMS; and a normal landing was made. Emergency services followed us to the ramp; and nothing abnormal was noted on the exterior of the airplane. All throughout the event the passengers were comfortable and we made them aware of the situation as we had time.After speaking with maintenance control; I was informed that this tail number had previously had a MAU failure. The controller said that after 10 hours of test flights they were unable to reproduce the failure. In order to help the crews know more about the different tail numbers that we fly; there needs to be a process [to check maintenance history]. We should be able to enter a tail number which we are assigned and review not only the current documents onboard and pass-down information but also recurring maintenance actions and abnormal maintenance irregularities for the previous 60-90 days. When the maintenance log sheets are removed from the aircraft; we are unable to see the full picture of the airplane and troubleshoot any minor problems.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.